The present invention relates to devices for covering at least a portion of the human eyelid, and more particularly, to a device to be located over the exterior surface of the inside or medial corner of an eye covering the juncture of the upper and lower eyelids in the areal of the nasolacrimal ducts.
Eye drops are designed to be absorbed through the front surface of the eye. The longer the medicine remains in contact with the eye, the better it is absorbed. Up to 90% of a drop, however, can be pumped away through the nasolacrimal duct before it has a chance to be absorbed into the eye.
Various studies have been made to determine the effects of different techniques of applying eye drops to the human eye. One such study is entitled, "Improving the Therapeutic Index of Topically Applied Ocular Drugs" and was published in the "Archives of Ophthalmology" April 1984, Volume 102 copyrighted by the American Medical Association. The concluding statement of this publication stated that, "In our experiments, we have observed a considerable reduction of systemic absorption of topical timolol by the simple procedures of NLO (nasolacrimal duct occlusion) (67% reduction) . . . Furthermore, these procedures increase the maximal concentration of fluorescein in the anterior chamber. These maneuvers increase corneal contact time and decrease the amount of drug delivered to the nasopharyngeal mucosa. Although only timolol and fluorescein were used in these experiments, theoretically, all topically applied drugs should manifest similar behavior. Generally, decreasing the amount of drug presented to the nasopharyngeal mucosa will decrease the systemic blood concentration of that drug. Similarly, prolonged corneal contact time will probably elevate intraocular concentration of a drug. Variability of dose-response curves and the bioavailability of a drug at receptor sites determine the degree to which ocular and systemic side effects are manifested.
Furthermore, . . . NLO . . . increased anterior chamber fluorescein concentration and duration of fluorescence. In most cases, this would allow a marked reduction of the applied concentration of the drug without loss of the desired ocular effect or duration of that effect and a further decrease in the possibility of systemic side effects. If the concentration cannot be decreased because of decreased desired effect, perhaps these procedures might permit a decrease in frequency of application.
With these techniques, even drugs contraindicated because of systemic side effects may be used with precautions, e.g., timolol in patients with asthma or epinephrine in patients with hypertension. Such clinical trials are underway.
In summary, five minutes of NLO . . . potentially improves the efficacy and potentially decreases the associated system side effects of topically applied ocular drugs."
By occluding the nasolacrimal duct for five minutes, the contact time of the drug to the ocular surface was greatly increased and significantly increased the penetration into the eye. This not only increases the intended effect of the drug but, by decreasing the amount of medication entering the blood stream through the nasopharyngeal surface, it also reduces the potential for systemic side effects.
The heretofore recommended technique of applying eye drops to the eye and performing nasolacrimal duct occlusion (NLO) is to apply a single eye drop to the open eye immediately place the forefinger over the upper eyelid one finger's breadth from the base of the nose and apply enough pressure downwardly to keep the eyelid firmly closed for at least, and preferably, five minutes.
A problem with this technique is that it requires an ophthalmologist significant time (10-15 minutes) to teach this technique to a patient. Even more importantly, typical patients resist using this technique because the technique is very difficult to perform properly and requires a relatively high level of dexterity. This is particularly difficult for older persons.
There are no devices known to me for preventing eye drops from entering the nasolacrimal duct system.